Nonionic polyelectrolytes

Polyelectrolytes are one of the most interesting and utiliz-able polymer materials presently under development. These water soluble polymers may be classified into three main groups nonionic polyelectrolytes, such as polyols, polyethers and polyamides anionic polyelectrolytes, such as carboxylates, sulfonates, and phosphates and cationic polyelectrolytes, such as ammonium, quaternary amines, sulfoniums and phosphoniums (1). These materials have wide and varied industrial applications. 

METHOD 3. Steric hindrance due to adsorption of an oriented nonionic polyelectrolyte... 

Two inorganic water-soluble polymers, both polyelectrolytes in their sodium salt forms, have been known for some time poly(phosphoric acid) (12) and poly(siHcic acid) (13). A more exciting inorganic water-soluble polymer with nonionic... 

Polyelectrolytes are classified into three main groups nonionic, anionic, and cationic depending upon the nature of the residual charge on the polymer in aqueous solution as shown in Table 1. 

In contrast to polyelectrolyte hydrogels, nonionic ones are almost insensitive to the ionic composition of the medium. In particular, the equilibrium swelling degree of a charge-free PAAm gel practically does not depend on the Cu2 + concentration (Fig. 4, curve 0) nor on the concentration of several other ions or on the pH value [101]. 

Assays. Nitrogen assays to determine 1-amidoethylene unit content were done by Kjeldahl method. Limiting viscosity numbers were determined from 4 or more viscosity measurements made on a Cannon-Fenske capillary viscometer at 30°C. Data was extrapolated to 0 g/dL polymer concentration using the Huggins equation(44) for nonionic polymers and the Fuoss equation(45) for polyelectrolytes. Equipment. Viscosities were measured using Cannon-Fenske capillary viscometers and a Brookfield LV Microvis, cone and plate viscometer with a CP-40, 0.8° cone. Capillary viscometers received 10 mL of a sample for testing while the cone and plate viscometer received 0.50 mL. 

A major drawback of synthetic thickeners when used with dyes is their sensitivity to electrolytes. Most soluble dyes behave as highly ionised electrolytes and disperse dyes contain anionic polyelectrolyte dispersing agents unless they have been formulated with nonionic systems specifically for use with acrylic thickeners. Consequently there is a loss of viscosity this can be quite pronounced although it depends on circumstances, particularly on the dye concentration. As already mentioned, this can be alleviated to some extent by copolymerisation with acrylamide during manufacture. Otherwise it is necessary to try to eliminate all electrolytes from the system or to increase the concentration of thickener. Such measures have their limitations in practice, however. Alternative synthetic thickening... 

For homopolyelectrolyte, we first studied the ellipsometric measurement of the adsorption of sodium poly(acrylate) onto a platinum plate as a function of added sodium bromide concentration (5). We measured the effect of electrolyte on the thickness of the adsorbed layer and the adsorbances of the polyelectrolyte. It was assumed that the Donnan equilibrium existed between the adsorbed layer and the bulk phase. The thickness was larger and the adsorbance of the polyelectrolyte was lower for the lower salt concentration. However, the data on the molecular weight dependence of both the adsorbance and the thickness of the adsorbed polyelectrolyte have been lacking compared with the studies of adsorption of nonionic polymers onto metal surfaces (6-9). 

Nolle AJ, Treat ND, Cohen RE, Rubner MF (2008) Effect of relative humidity on the Young s modulus of polyelectrolyte multilayer films and related nonionic polymers. Macromolecules 41 5793-5798... 

Polyelectrolytes may be synthesized by a variety of post-functionalization techniques in which ionogenic groups are introduced into the structure of an existing nonionic polymer. For an excellent review of polymer functionalization reactions the reader is referred to the recent book by Akelah and Moet [65]. In this paper, representative examples of the major polymer modification techniques for polyelectrolyte synthesis will be presented. 

The thermodynamics of weakly charged polyelectrolyte solutions have been the subjects of several recent investigations [110-112]. In these systems, the properties are intermediate between nonionic polymers and fully charged polyelectrolytes and both electrostatic and nonionic interactions can be important in determining the polymer characteristics. 

The role of polymers on colloid stability is considerably more complicated than electrostatic stability due to low molecular weight electrolytes considered in Chapter 11. First, if the added polymer moieties are polyelectrolytes, then we clearly have a combination of electrostatic effects as well as effects that arise solely from the polymeric nature of the additive this combined effect is referred to as electrosteric stabilization. Even in the case of nonionic... 

To summarize, we have shown that proton transport and reaction with unionized amines is often a decisive factor in determining swelling rates in the hydrophobic amine gels we have studied. Simple explanations based on solvent diffusion and polymer relaxation, although useful for nonionic polymers, cannot account for swelling kinetic phenomena in initially dry polyelectrolyte gels. 

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